Obesity is rapidly reaching epidemic proportions in developed societies worldwide. There are currently over 1 billion overweight people globally, with 300 million of these people considered clinically obese. In the United States alone there are more than 50 million obese adults, and the numbers are expected to increase by more than 50% in the next decade. Morbid obesity (i.e. obesity in which there are secondary complications such as hypertension, diabetes, coronary artery disease, stroke, congestive heart failure, orthopedic problems and pulmonary insufficiency) not only affects quality of life, but also shortens life expectancy and costs the health care industry billions of dollars annually.
Interventional procedures and associated medical devices for treating morbid obesity in patients are well known in the art. In general, these interventional procedures promote weight loss by either (a) gastric restriction or volume reduction, (b) malabsorption, or (c) a combination of the foregoing. Gastric restriction or volume reduction methods promote weight loss by limiting the amount of food intake (i.e. the patient eats less), either due to physical space limitation or by inducing a feeling of early satiety in the patient. Malabsorption methods promote weight loss by limiting the uptake of nutrients (i.e. the patient digests less of what is eaten), usually by removing or bypassing a portion of the gastrointestinal (GI) tract.
Among the earliest interventional procedures directed at promoting weight loss were variations of the jejuno-ileal bypass developed in the 1950s. This surgery effectively bypasses the small intestine and is therefore a strictly malabsorption procedure, which poses serious risks. The bilopancreatic diversion procedure, which combines bypass of most of the small intestine with a partial gastrectomy, is a combined volume reduction and malabsorption procedure that was developed in effort to reduce these risks, but it too had complications and its success was limited.
Roux-en-Y gastric bypass surgery is a commonly performed bariatric procedure, especially in the US. It was originally performed as an open interventional procedure, but it is now routinely performed laparoscopically. This procedure utilizes interventional stapling and cutting devices to form a small stomach pouch, bypassing the lower part of the stomach, and creates a Roux-en-Y limb to attach the jejunum to the pouch. The Roux-en-Y procedure is predominantly a volume reduction method (the stomach pouch is typically ˜25 cc in volume), although there is a significant malabsorption component.
Despite the proven efficacy of the Roux-en-Y procedure in terms of achieving weight loss, and the recent laparoscopic improvements that have reduced the associated interventional risks, it remains a highly invasive procedure with substantial rates of morbidity. The rate of interventional mortality may be as high as 1%, and known complications include frequent pulmonary morbidity and anastomotic leaks that can be life threatening. Furthermore, the malabsorption component of the Roux-en-Y procedure can negatively affect health because of reduced vitamin uptake, and the long-term consequences of malabsorption are not yet fully understood.
A variety of other interventional procedures have also been developed involving the use of interventional stapling to bring together and fasten opposing walls of the stomach in order to reduce its volume. Most involve malabsorption to a greater or lesser extent, depending on the procedure. Examples of such procedures include the horizontal gastroplasty (HG) and vertical banded gastroplasty (VBG), as well as more recent variations such as the Magenstrasse and Mill (M&M) and laparoscopic sleeve gastrectomy (LSG) procedures that involve not only stapling, but cutting away and removal of the unused stomach portion, leaving behind a reduced volume tube or sleeve running more or less parallel to the lesser curvature between the esophagus and the pylorus. Surgically inserted artificial sleeves that longitudinally traverse the stomach may achieve similar effective volume reductions while significantly increasing malabsorption. In any case, weight loss results achieved with these procedures may sometimes approach those of the Roux-en-Y, however these procedures are not easily performed, are difficult if not impossible to reverse, and still suffer from risks of serious complications, most frequently related to failure or leakage of the staples, which can lead to dangerous infections and even death.
An alternative minimally invasive procedure recently growing in popularity involves the laparoscopic placement of an adjustable silicone ring around the upper portion of the stomach, thereby creating a small (e.g. 50-120 cc) pouch. The LAP-BAND® is one such commercially available restrictive device that, after placement, induces a feeling of early satiety in the patient. Although considerably less invasive than the Roux-en-Y procedure, and potentially reversible, significantly less weight loss has been observed with laparoscopic banding. This procedure also suffers from a variety of limitations and shortcomings. For example, because the laparoscopic band does not actually reduce the volume of the stomach, some patients report a feeling of nearly constant hunger. Additionally, long-term complications of the laparoscopic banding procedure may include tissue erosion, slippage of the band, infection, or lack of effectiveness, frequently requiring removal of the band after a period of time.
Another less invasive alternative to the above-mentioned procedures is the intragastric balloon. The intragastric balloon is an inflatable device that is deployed within the stomach, thereby displacing a known internal volume. The advantages of this method are that it is minimally invasive, involves no malabsorption component, and requires no stapling, permanent reconfiguration or removal of tissue. While the correlation between apparent stomach volume reduction and weight loss is well established by the intragastric balloon method, the weight loss achieved is typically considerably less than with Roux-en-Y. Furthermore, unless it is surgically fastened to the stomach wall, the balloon is free floating and frequent complications such as obstruction, mucosal erosion, nausea, vomiting and pain have been documented, with the result that intragastric balloons are usually removed within 6 months after initial placement.
In effort to develop even less invasive devices and procedures, more recently there has been considerable interest in various transoral (or transesophageal) endoscopic approaches for reducing stomach volume entirely from within the gastrointestinal lumen, without the need for abdominal incisions. In general, these approaches involve advancing an endoscope down the patient's esophagus and into the stomach, whereby various tools are then used to manipulate and reconfigure the stomach tissue in order to create one or more divisions or internal folds (also known as plications) within the stomach wall. To securely hold the divisions or plications so formed, some form of sutures, staples, anchors, or other similar securing means are placed transesophageally through the stomach walls, and sophisticated endoscopic tools have been developed for such purposes. Tissue approximation and fixation devices for use in endoscopic procedures are described, for example, in U.S. Patent Publications 2004/0215216, 2007/0112364, 2005/0080438. Many other types of endoscopic tissue approximation and fixation devices and fasteners are also known in the art.
While quite promising, endoscopic approaches for reducing stomach have various limitations and shortcomings. For example, they must be performed by highly skilled endoscopic surgeons and involve the use of large, complicated endoscopic devices that require specialized training to deal with the restricted access and small working space. In order to access the stomach internally, devices must be passed down the patient's esophagus, accruing a substantial risk of perforating the esophagus and injuring adjacent organs. In addition, capturing and manipulating the tissue layers and accurately applying the securing means during a transesophageal procedure is not only difficult but also hazardous, due to the significant risk of accidental injury to other organs, bleeding, etc., when piercing (intentionally or accidentally) the stomach wall. Because there is no extragastric visualization in these procedures, there is no advance warning of a developing life threatening situation that may require a rescue operation.
The stomach wall is comprised of four main tissue layers. The mucosal layer is the innermost tissue layer, adjacent a submucosal connective tissue layer. The submucosal connective tissue layer interfaces with the muscularis layer, and the serosal layer covers the exterior (extragastric) surface. Prior art gastric reduction procedures involving tissue reconfiguration from inside the stomach require the placement of sutures, staples, or anchors during surgery to hold the reconfigured tissue in place strongly enough to sustain the tensile loads imposed by normal movement of the stomach wall during ingestion and processing of food. Because the mucosal and submucosal connective tissue layers are relatively weak and prone to elastic stretching during digestion, the securing means generally penetrate the stomach wall to engage at least the muscularis layer. For this reason, the prior art securing means are generally transgastric, passing one or more times completely through the stomach wall.
Proper use and placement of fasteners that penetrate the gastric wall is challenging and concentrates significant forces over a small surface area of mucosal tissue, thereby potentially causing the suture, staple or anchor to leak or tear through the tissue, with potentially disastrous consequences. It is well known that the fasteners used in these procedures frequently migrate, dislodge or even completely disappear over time, resulting in partial or complete failure to maintain the gastrointestinal volume reduction, as well as possible complications. These are significant limitations and shortcomings of prior art bariatric procedures involving tissue reconfiguration.
Previously known interventional procedures for treating obesity through gastrointestinal volume reduction or malabsorption thus involve numerous risks, including life-threatening post-operative complications (e.g. internal bleeding, infection), and long-term problems such as diarrhea, vitamin deficiency, electrolytic imbalance, unpredictable or insufficient weight loss, and gastrointestinal reflux disease (GERD). Given the above noted shortcomings, limitations and risks of prior art procedures, it is apparent there remains a need for safe, easy-to-perform and effective interventional procedures for reducing gastric volume, as well as for devices enabling such procedures.